Process method for improving bending performance of copper strip used in solar photovoltaic field

Abstract

The invention relates to the technical field of copper alloys, in particular to copper alloy performance optimization, and particularly relates to a process method for improving the bending performance of a copper strip used in the solar photovoltaic field. The invention discloses a process method for improving the bending performance of a copper strip in the solar photovoltaic field. Comprising the following steps of smelting, casting, stepping furnace heating, hot rolling, surface milling, primary cold rolling, edge cutting, primary annealing, semi-finished product cleaning, secondary cold rolling, secondary annealing, pre-finished product cleaning, third cold rolling, finished product cleaning, pulling and straightening, slitting and packaging. The bending performance of the C19210 copper strip used in the solar photovoltaic field is improved through control over the smelting component Fe element, precise control over matched heat treatment parameters and cooperation with the reasonable cold deformation machining degree, the tensile strength of the copper strip is 340-390 MPa, the A11.3 elongation is larger than or equal to 10%, the hardness HV value is 105-125, and no obvious crack exists in a 90-degree bending test in the strip rolling direction and the direction perpendicular to the strip rolling direction.

Description

Technical Field

[0001] The invention relates to the technical field of copper alloys, and in particular to the optimization of copper alloy performance, and specifically to a process method for improving the bending performance of copper strips used in the field of solar photovoltaics. Background Art

[0002] C19210 copper alloy material has the characteristics of high strength, high conductivity and excellent processing characteristics. It is suitable for conductive components in photovoltaic junction boxes and IGBT modules in inverters. Some high-end products need to be bent 90° during processing without cracking. The copper alloy strip has the following composition (Fe: 0.05-0.15%; P: 0.025-0.040%; the rest is copper and unavoidable impurities).

[0003] At present, the performance index requirements of C19210 copper strip used in the solar photovoltaic field are: tensile strength 320-410; A 50 Elongation ≥6%; Hardness HV 100-125; Electrical conductivity ≥85%IACS; No obvious cracks in the 90° bending test along the strip rolling direction and perpendicular to the strip rolling direction with R / T=1.0 (where R is the bending radius and T is the strip thickness). Summary of the invention

[0004] In order to solve the problem that copper strips for solar photovoltaics need good bending performance, the present invention provides a process method for improving the bending performance of copper strips for solar photovoltaics. The present invention improves the bending performance of copper strips by using technical means in ingot composition control, heat treatment processing and deformation processing to meet the quality requirements of subsequent performance processing of copper strips for photovoltaics. A 90° bending test is performed with R / T=1.0, and no obvious cracks are found.

[0005] The present invention is implemented by adopting the following technical scheme: a process method for improving the bending performance of copper strip used in the field of solar photovoltaic, comprising the following steps: smelting → casting → heating in a walking furnace → hot rolling → milling → primary cold rolling → trimming → primary annealing → semi-finished product cleaning → secondary cold rolling → secondary annealing → pre-finished product cleaning → tertiary cold rolling → finished product cleaning → straightening → slitting → packaging.

[0006] (1) Melting Smelting composition control: Fe element 0.06-0.10%.

[0007] (2) Stepping furnace heating The heating temperature is 950℃-970℃, and the temperature fluctuation in the furnace does not exceed the range value ±15℃.

[0008] (3) Hot rolling The online quenching temperature is 560-610℃, the working roll pairing difference is ≤0.8mm, and the working roll surface roughness Ra value is 2.0~3.5μm.

[0009] (4) Milling The milling amount of the upper and lower surfaces is 0.8-1.0mm each, and the milling amount of the two side surfaces is 2.5-3mm each.

[0010] (5) Primary cold rolling The rolling processing rate of each pass is ≤30%, the working roll pairing difference is ≤0.04mm, and the working roll surface roughness Ra value is 0.4-0.6μm.

[0011] (6) Primary annealing The annealing temperature range is 500-550℃, and the holding time is 6-8h.

[0012] (7) Secondary cold rolling The total processing rate is 40-60%, the rolling processing rate of each pass is ≤25%, the working roll pairing difference is ≤0.03mm, and the surface roughness Ra value of the working roll is 0.25-0.3μm.

[0013] (8) Secondary annealing The annealing temperature range is 450-480℃, and the holding time is 6-8h.

[0014] (9) Three-stage cold rolling The total processing rate is 20-25%, the rolling processing rate between each pass is ≤18%, the working roll pairing difference is ≤0.02mm, and the working roll surface roughness Ra value is 0.10-0.15μm.

[0015] Through the control of the above smelting component Fe element, the precise control of matching heat treatment parameters, and the reasonable degree of cold deformation processing, the bending performance of C19210 copper strip used in the solar photovoltaic field can be improved.

[0016] Function 1 of iron: In C19210 copper strip, iron can play a role in precipitation strengthening. Iron forms a fine dispersed phase in the copper alloy. When the copper alloy is cooled from high temperature, iron atoms will precipitate in the form of specific compounds, which are dispersed in the copper matrix.

[0017] The second role of iron: After the copper strip undergoes rolling and other processing, work hardening will occur. When annealing is performed, recrystallization generally occurs. Iron can inhibit the occurrence of recrystallization or slow down the rate of recrystallization. This is because iron atoms at the grain boundary or inside the lattice interfere with the formation and growth of crystal nuclei during the recrystallization process. This allows the copper strip to maintain a certain work hardening effect after annealing, that is, maintain a high strength and appropriate toughness, which is conducive to improving the bending resistance.

[0018] Choosing an appropriate ratio of iron content can improve the material's bending resistance while maintaining high strength.

[0019] Cold deformation processing: Cold deformation processing increases the dislocation density inside the material, and the dislocations are entangled with each other, forming a cellular structure that hinders the movement of dislocations, increasing the number of immovable dislocations, so that greater force is required to enable the dislocations to overcome obstacles and move. The greater the degree of deformation, the greater the deformation resistance of the strip and the higher the strength. Therefore, a reasonable rolling processing rate should be selected to ensure that the deformation resistance is not too large.

[0020] The above-mentioned process for improving the bending performance of copper strips used in the field of solar photovoltaics has a copper alloy grade of C19210 and a product thickness of 0.7 mm or 0.8 mm.

[0021] The effect of the present invention is: the tensile strength of C19210 copper strip used in the solar photovoltaic field is 340-390MPa, A 11.3 Elongation ≥ 10%, hardness HV value 105-125, 90° bending test along the strip rolling direction and perpendicular to the strip rolling direction with R / T=1.0, no obvious cracks. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with embodiments. Embodiment 1

[0023] A process for improving the bending performance of a copper strip for use in the field of solar photovoltaics comprises the following steps: smelting → casting → heating in a stepping furnace → hot rolling → milling → primary cold rolling → trimming → primary annealing → semi-finished product cleaning → secondary cold rolling → secondary annealing → pre-finished product cleaning → tertiary cold rolling → finished product cleaning → straightening → slitting → packaging.

[0024] (1) Melting Smelting composition control: Fe element 0.10%.

[0025] (2) Stepping furnace heating The heating temperature is 970℃, and the temperature fluctuation in the furnace does not exceed the range value of ±15℃.

[0026] (3) Hot rolling The online quenching temperature is 610℃, the working roll pairing difference is 0.8mm, and the working roll surface roughness Ra value is 3.5μm.

[0027] (4) Milling The milling amount of the upper and lower surfaces is 1.0mm each, and the milling amount of the two side surfaces is 3mm each (5) Primary cold rolling The rolling processing rate of each pass is 26-30%, the working roll pairing difference is 0.04mm, and the surface roughness Ra value of the working roll is 0.6μm.

[0028] (6) Primary annealing The annealing temperature range is 550℃ and the holding time is 8h.

[0029] (7) Secondary cold rolling The total processing rate is 60%, the processing rate of each rolling pass is 22-25%, the working roll pairing difference is ≤0.03mm, and the surface roughness Ra value of the working roll is 0.3μm.

[0030] (8) Secondary annealing The annealing temperature range is 480°C and the holding time is 8h.

[0031] (9) Three-stage cold rolling The total processing rate is 25%, the rolling processing rate between each pass is 15-18%, the working roll pairing difference is 0.02mm, and the working roll surface roughness Ra value is 0.15μm.

[0032] The effect of the present invention is: the tensile strength of C19210 copper strip used in the solar photovoltaic field is 372MPa, A 11.3 The elongation is 13%, the hardness HV value is 116, and there is no obvious crack in the 90° bending test along the strip rolling direction and perpendicular to the strip rolling direction with R / T=1.0.

[0033] The above-mentioned process method for improving the bending performance of copper strips used in the solar photovoltaic field has a copper alloy grade of C19210 and a product thickness of 0.7 mm. Embodiment 2

[0034] A process for improving the bending performance of a copper strip for use in the field of solar photovoltaics comprises the following steps: smelting → casting → heating in a stepping furnace → hot rolling → milling → primary cold rolling → trimming → primary annealing → semi-finished product cleaning → secondary cold rolling → secondary annealing → pre-finished product cleaning → tertiary cold rolling → finished product cleaning → straightening → slitting → packaging.

[0035] (1) Melting Smelting composition control: Fe element 0.06%.

[0036] (2) Stepping furnace heating The heating temperature is 950℃, and the temperature fluctuation in the furnace does not exceed the range value of ±15℃.

[0037] (3) Hot rolling The online quenching temperature is 560℃, the working roll pairing difference is 0.5mm, and the working roll surface roughness Ra value is 2.0μm.

[0038] (4) Milling The milling amount of the upper and lower surfaces is 0.8mm each, and the milling amount of the two side surfaces is 2.5mm each (5) Primary cold rolling The rolling processing rate of each pass is 22-25%, the working roll pairing difference is 0.02mm, and the surface roughness Ra value of the working roll is 0.4μm.

[0039] (6) Primary annealing The annealing temperature range is 500°C and the holding time is 6h.

[0040] (7) Secondary cold rolling The total processing rate is 40%, the processing rate of each rolling pass is 18-21%, the working roll pairing difference is 0.02mm, and the surface roughness Ra value of the working roll is 0.25μm.

[0041] (8) Secondary annealing The annealing temperature range is 450°C and the holding time is 6h.

[0042] (9) Three-stage cold rolling The total processing rate is 20%, the rolling processing rate between each pass is 12-15%, the working roll pairing difference is 0.01mm, and the working roll surface roughness Ra value is 0.10μm.

[0043] The effect of the present invention is: the tensile strength of C19210 copper strip used in the solar photovoltaic field is 352MPa, A 11.3 The elongation is 18%, the hardness HV value is 109, and there is no obvious crack in the 90° bending test along the strip rolling direction and perpendicular to the strip rolling direction with R / T=1.0.

[0044] The above-mentioned process for improving the bending performance of copper strips used in the solar photovoltaic field has a copper alloy grade of C19210 and a product thickness of 0.8 mm. Embodiment 3

[0045] A process for improving the bending performance of a copper strip for use in the field of solar photovoltaics comprises the following steps: smelting → casting → heating in a stepping furnace → hot rolling → milling → primary cold rolling → trimming → primary annealing → semi-finished product cleaning → secondary cold rolling → secondary annealing → pre-finished product cleaning → tertiary cold rolling → finished product cleaning → straightening → slitting → packaging.

[0046] (1) Melting Smelting composition control: Fe element 0.075%.

[0047] (2) Stepping furnace heating The heating temperature is 963℃, and the temperature fluctuation in the furnace does not exceed the range value of ±15℃.

[0048] (3) Hot rolling The online quenching temperature is 575℃, the working roll pairing difference is 0.6mm, and the working roll surface roughness Ra value is 2.8μm.

[0049] (4) Milling The milling amount of the upper and lower surfaces is 0.9mm each, and the milling amount of the two side surfaces is 2.7mm each (5) Primary cold rolling The rolling processing rate of each pass is 24-28%, the working roll pairing difference is 0.03mm, and the surface roughness Ra value of the working roll is 0.48μm.

[0050] (6) Primary annealing The annealing temperature range is 525°C and the holding time is 7h.

[0051] (7) Secondary cold rolling The total processing rate is 52%, the processing rate of each rolling pass is 20-23%, the working roll pairing difference is 0.02mm, and the surface roughness Ra value of the working roll is 0.27μm.

[0052] (8) Secondary annealing The annealing temperature range is 471°C and the holding time is 7h.

[0053] (9) Three-stage cold rolling The total processing rate is 23%, the rolling processing rate between each pass is 13-19%, the working roll pairing difference is 0.02mm, and the working roll surface roughness Ra value is 0.12μm.

[0054] The effect of the present invention is: the tensile strength of C19210 copper strip used in the solar photovoltaic field is 355MPa, A 11.3 The elongation is 16%, the hardness HV value is 113, and there is no obvious crack in the 90° bending test along the strip rolling direction and perpendicular to the strip rolling direction with R / T=1.0.

[0055] The above-mentioned process for improving the bending performance of copper strips used in the solar photovoltaic field has a copper alloy grade of C19210 and a product thickness of 0.8 mm.

Claims

1. A process for improving the bending performance of copper strips used in the field of solar photovoltaics, comprising the following steps: Melting → casting → heating in a walking furnace → hot rolling → milling → first cold rolling → trimming → first annealing → semi-finished product cleaning → second cold rolling → second annealing → pre-finished product cleaning → third cold rolling → finished product cleaning → straightening → slitting → packaging; Its characteristics are: (1) Melting Smelting composition control: Fe element 0.06-0.10%; (2) Stepping furnace heating Heating temperature is 950℃-970℃, and the fluctuation temperature in the furnace does not exceed the range value ±15℃; (3) Hot rolling Online quenching temperature 560-610℃, working roll pairing difference ≤0.8mm, working roll surface roughness Ra value 2.0~3.5μm; (4) Milling The milling amount of the upper and lower surfaces is 0.8-1.0mm each, and the milling amount of the two side surfaces is 2.5-3mm each; (5) Primary cold rolling The rolling processing rate of each pass is ≤30%, the working roll pairing difference is ≤0.04mm, and the working roll surface roughness Ra value is 0.4-0.6μm; (6) Primary annealing Annealing temperature range 500-550℃, holding time 6-8h; (7) Secondary cold rolling The total processing rate is 40-60%, the rolling processing rate of each pass is ≤25%, the working roll pairing difference is ≤0.03mm, and the working roll surface roughness Ra value is 0.25-0.3μm; (8) Secondary annealing Annealing temperature range 450-480℃, holding time 6-8h; (9) Three-stage cold rolling The total processing rate is 20-25%, the rolling processing rate between each pass is ≤18%, the working roll pairing difference is ≤0.02mm, and the working roll surface roughness Ra value is 0.10-0.15μm.

2. A process for improving the bending performance of copper strips used in the field of solar photovoltaics according to claim 1, characterized in that: The copper alloy grade is C19210 and the product thickness is 0.7mm or 0.8mm.